Gents-
I will say right up front that I am pretty much allergic to most things electrical. I'd be mighty greatful if someone can follow my story here and help me.

I bought a 53 Chevy 210 at the NSRA Nationals two years ago. It's a great looking car, ran and drove OK, but was all pretty much stock drivetrain. The body, paint and interior were all done. I installed a fresh 350/350, Chassis Engineering MII, 10 bolt, Ididit column, etc etc. and now I can't drive the car because of a wiring problem of some kind. Here's the symptom:

Engine running, lights on, I noticed what I can only describe as a "blink" in the headlights and dashlights. They go bright for only a moment, then back to normal. Last time it happened, I was just watching it, trying to figure it out, and when it "blinked" it was such a surge in voltage that it actually blew out both headlights. Ok, says I, only thing that can create that much juice is the alternator/regulator, (GM single wire) so I take if off, take it to a rebuild shop here in Denver, and have it redone. Put it back on, no good. Problem persists. A buddy said I needed a ground strap, I added two. One from the block to the frame, one from the body to the frame. No good, problem persists. I also notice that when the engine is running, I see every so often the voltmeter changing from 12.5 to about 10, random, but every few minutes. I break down, and take the car to a local electrical repair shop. $300 later, they tell me that my headlights are out, and if it happens again, to bring it back. . So, here I am.

Like I said, I am not any good at electrical. The car had been rewired prior to my having it, but the job really looks pretty haphazard. If anyone can help me I'd be really greatful. If you know someone in the Denver area who is good at this stuff, I'd be willing to $$ them to get this right before the season is over. I'd like to drive this car without worrying about it catching -fire or something... call me if you'd like at (303) 681-7770.

I would add a strap from block to body and replace the alternator. It sounds like a bad regulator. Just because you took it to s shop doesn't mean they fixed it. Can you swap one from a buddy's' ride ?

This may sound dumb by was all of the lights changed over to 12v? I think the 53's came out factory as 6v. It sounds like something with the voltage regulator in the alternator. I would buy an alternator.

Why did you pay an "electrical repair shop" $300.00 to tell you something you already knew?
Voltage changing from 12.5 down to 10 would cause the lights to dim not go bright.
If the shop said bring it back I would. Sounds like ya got about 3 or so hours of work comming from them.

Is the alt a true one wire or a three wire wired as a one wire? The three wire would have a wire from the #2 terminal straight to the lg output lug on the back of the alt.....hence a one wire. If it's a true three wire, I'd remove the wire from the #2 terminal and the lg output lug. run a new wire, 10 guage or so and about 4-5 foot long, to the main hot wire going into the fuse box/pos post on the battery.

The #2 terminal is the sense wire and tells the alt how much juice to put out, on 60's era car's GM originaly ran this from the alt to a radiator support terminal/junction, then across the radiator support to the drivers side then tied into a fuseable link and into the pos side of the electrical system to take avantage of the resistance the long wire run provied....... getting a truer sense of the demands on the electrical system etc.....

I'm thinking your alt is getting a false signal to produce more juice etc.. The temp wire will prove/disprove that etc......

I had a chevy van that was a great van. One night on my way home the voltage spiked up to about 18 volts, headlights bright and all.
I put a new voltage regulator in it. Done deal.
It was an internal regulated SI series.

All the bulbs are 12 volt. I'll be d---med if I'll ever take my car back to the shop that ripped me off. I paid my bill, but I was very clear that my big mouth was going to cost them a lot more than $300 worth of business. Didn't seem to bother them any.

I have NO idea if it's a three or one wire. I can tell you it's chrome plated, and has a single stud on the back of it. I'd guess that it would be a single wire, but I know that aftermarket, chrome plated three wire alternators are out there. I have forgotten where I got this, so I can't say what it was represented as.

I'll try to get out tonight and take a look at it. My next day off is Wednesday, so I may see about running that test lead, thanks.

I would add a strap from block to body and replace the alternator. It sounds like a bad regulator. Just because you took it to s shop doesn't mean they fixed it. Can you swap one from a buddy's' ride ?

Okay, tonight I was finally able to get over to the shop and examine things in light of your comments. First, it's clearly a three wire alternator. Second, it only has one wire going to it, and it is the large wire that goes straight to the positive side of the starter, where it meets the battery cable. The terminals on the back of the alternator are not marked one or two. The one shown above two is the furthest one from the battery location; a quick check on a buddy's showed the same thing. So I made a short section of wire going from what should be #2 to the battery terminal and started it up. The volt meter in the car was steady at just short of 13 volts, pretty constant the whole time. Then the light thing started it's blink thing again, did it a few times, I shut the car off. I have not run a ground from the engine to the body. I do have grounds running from the body to the frame and from the engine to the frame.

Any guesses? I'm getting closer to bald all the time. Thanks for all the thinking and help.

EOD-
Thanks for the help, I'm not going to ask why you're up at 3:30 in the morning...

OK, let me make sure I have this right. I need to scrap the little 2" wire thing I made, and run a pretty heavy, like 10 gauge wire, from #2 to the battery itself (starter), and run a second wire from #1 to a switched 12 volt, like the "on" position on the ignition switch or something?

You should be able to maintain a constant 14volts give or take .2 volts with a fully charged battery.
I would be willing to bet you have a couple issues which makes it more difficult to diagnose.
First you need a good multimeter to see what the voltage really is at different points in the system.
You need to pull the battery and have it charged and tested. Recently I have seen batteries cause weird issues.
You need to be sure of exactly what you have for an alternator. A one wire is a waste of time in my opinion and will not necessarily work properly when the other wires are connected. The voltage regulator is the main difference between a one wire and a three wire.
There is a small d shaped hole in the back of the alternator. In that hole there is a little metal tab. If you carefully insert a small screwdriver into that hole and ground that tab it will force full output on the alternator. This may help you test it.

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